The present invention refers to a method of and a compression tube for increasing pressure of a flowing gaseous medium, further to a power machine applying the proposed compression tube. According to the art the method of the invention comprises the steps of accelerating flow of a gaseous medium to a supersonic velocity, impacting the supersonic flow of the gaseous medium into a space including shock waves and decelerating thereby the supersonic flow of the gaseous medium to a subsonic velocity range. The compression tube consists of tube sections arranged along the path of flow of the gaseous medium in a linear system, wherein the first of the tube sections is an accelerating element, then a transient tube section and outlet means follow. The power machine as proposed includes an inlet section for inducing flow of a gaseous medium, a compressor for increasing pressure of the gaseous medium, power transformation means for producing mechanical work on the basis of the gaseous medium received and exhaust means for expelling remainings of the gaseous medium, wherein the an inlet section, compressor, power transformation means and exhaust means form a linear arrangement, they are divided and connected in the linear arrangement by respective pipeline sections.
The increase of the pressure (the compression) of the gaseous media is generally intended to ensure continuous volume or mass transfer, because of the possibility of ensuring the volume or mass transfer (an "extensive" variable of the thermodynamic process) by means of an appropriate pressure gradient (an "intensive" variable of the thermodynamic process).
In order to increase the pressure of a gaseous medium it is always necessary to assure energy transport, i.e. to produce work. Thus, the compression process can be completed by mechanical, thermal and electromagnetic effects, however, other physical and chemical processes are also applicable for this purpose.
The present invention proposes the compression process to be completed by the use of aerodynamic forces. In this case there is a continuous path within the space of flowing the gaseous medium, there is no separation between the high and low pressure space parts. The pressure difference between two points of the aerodynamic arrangement is maintained by changing the impulse per unit of the volume in the flow of the gaseous medium. The energy transfer required in this process can be expressed by the means of the enthalpy of the gas. The general theory of the aerodynamic machines of this kind is the subject of the book of Shapiro, A. M.: The Dynamics and Thermodynamics of Compressible Fluid Flow (Roland Press, New York, 1953, chapter 8, especially pages 228 to 231). The special problems arising with application of the supersonic flow of a gaseous medium are the subject of the article of Abdulhadi, M. (Dynamics of Compressible Air Flow with Friction in a Variable-area Duct, Warme- und Stoffubertragung, 22, 1988, pages 169 to 172).
A control device for a pumping system incorporating fluidic devices is shown in the GB patent application No. 2 170 324 filed in January 1985 (in the name of British Nuclear Fuels plc). The fluidic device being the merit of this application has an air inlet leading to a convergent/divergent nozzle, particularly a Laval nozzle producing supersonic velocity flow. A compressive shock wave is produced just upstream of an intake of a diffuser applied for decelerating the flow of the air. This device can be used in a pumping system, e.g. in a system incorporating a reverse flow diverter.
The geometric arrangement of the device described in the GB-A 2 170 324 mentioned above is very advantageous for increasing pressure during the operation of a pumping system. The shock waves produced by means of an intake (e.g. an Oswatitsch intake or other) consume relatively high amounts of energy, and thus the enthropy increase of the flow is disadvantageous. This device discloses the possibility of practical application of supersonic velocity flow for increasing pressure of a fluid medium. However, the application is limited to fluidic pumps.
In different technical fields the injectors (and ejectors) are widely used when increased pressure of a gaseous or liquid medium flowing in a tube is required. The injectors and ejectors are very simple, but they show low efficiency. They comprise a nozzle for accelerating the flow of a gaseous or liquid medium, a transient tube section and outlet means. The increased pressure results from the application of a diffuser in the outlet means.
The efficiency of the power machines, and especially of the gas turbines can be improved by applying combustors and other means for generating a stagnation-pressure increase, instead of the customary loss of stagnation pressure that occurs with conventional steady flow combustors (as stated e.g. in the article of Kentfield, J. A. C. and O'Blenes, M. (Methods for Achieving a Combustion-Driven Pressure Gain in Gas Turbines, Transaction of the ASME, vol. 110, 1988, October, pages 704 to 710). The recognition of the authors described in this article refers only to the combustion process realised in the gas turbines.